1. Field of the Invention
Methods consistent with the present invention relate to compressing and restoring an Internet Protocol (IP) packet which is transmitted through a broadcast network, and more particularly, to compressing an IP packet by using a characteristic of a transmission structure of a broadcast network, that is unlike ordinary packet switching communication networks, by which a field value that can be removed from a header part of an IP packet is determined, the determined field value is removed from the header, and an IP packet having a header formed with the remaining field values is generated, and to restoring the compressed IP packet.
2. Description of the Related Art
FIG. 1 is a schematic diagram illustrating a method of transmitting IP packets through a broadcast network according to conventional technology.
In an ordinary process for broadcasting multimedia content through a broadcast network, first, a content provider generates the multimedia content as a data stream. Then, in order to transmit the data through networks, the data is fragmented into smaller IP packets.
A receiving end receives the plurality of IP packet fragments, multiplexes the packets, and finally broadcasts the packets to unspecified multiple users. Since a broadcast network generally transmits data to multiple users as receivers, data is not exchanged in a state in which a 1:1 or N:1 communication path is established. The broadcast network should also consider users who randomly access broadcast channels.
When data is broadcast in this way, the conventional method compresses an IP packet by using omission of redundant data in the header of the IP packet in order to reduce the size of the IP packet to be transmitted.
Referring to FIG. 1, when time points are expressed as t, t+1, t+2, . . . , t+n, according to the conventional method, a static IP packet which is not compressed is transmitted at time t. An IP packet including a header having a differential value with respect to the previous IP header (at time t) is transmitted at time t+1. However, since unspecified multiple users can access broadcast channels at an arbitrary time while packets are transmitted, a static IP packet having a whole header should be transmitted periodically. Accordingly, an IP packet which is not compressed is transmitted at time t+n as illustrated in FIG. 1.
However, since the static IP packet appearing in the conventional method is not compressed, a method of improving the conventional technology is necessary.